fix(web): restore pointer cursor affordances

[Cvv9]

Summary

• restore pointer cursors for enabled buttons, links, summaries, tabs, and menu-item roles in Buzz Web
• preserve default cursors for disabled and aria-disabled controls
• add Chromium regression coverage for enabled, text-input, and disabled cursor states

Validation

• ./scripts/with-toolchain.ps1 pnpm --dir web build
• focused Playwright cursor regression (passed)
• ./scripts/with-toolchain.ps1 pnpm --dir web check (138 tests passed)